The most common commercial method involves treatment of the skins with water containing up to 3000 ppm of sulfur dioxide or its equivalent in bisulfite or metabisulfite. After 48 to 72 h, the liquid is removed from the skins, filtered, desulfured, and concentrated. Sometimes a fermentation step is allowed prior to the extraction, in which case the alcohol is removed during subsequent processing. The final product is a particle-free liquid of high tinctorial power. The concentrated liquid may also be dried to produce a soluble dry powder. The presence of sulfur dioxide in the extracting medium results in increased extraction of the pigments as well as increased stability of the final product. The sulfite-anthocyanin complex is colorless, so the sulfite must be removed prior to the final concentration and filtration step. Addition of acid makes the extraction step more efficient, but addition of mineral acid requires neutralization at some point. The addition of tartaric acid can
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Salvation For The Sleep Deprived The Ultimate Guide To Sleeping, Napping, Resting And Restoring Your Energy. Of the many things that we do just instinctively and do not give much of a thought to, sleep is probably the most prominent one. Most of us sleep only because we have to. We sleep because we cannot stay awake all 24 hours in the day.